1. Field of the Invention
The present invention relates to coordination compounds, and particularly to tristhiourea tripodal metal complexes that include a transition metal bonded to a chelating agent having three thiourea ligands bridged by TAPA [tris(6-amino-2-pyridylmethyl)amine] that forms a tripodal cavity, making the compounds good anion receptors suitable for use in colorimetric sensors, selectively permeable membranes, filtration media for separations, etc.
2. Description of the Related Art
The use of molecular sensors is a unique method for the detection of species. Anions play an important role in a wide range of chemical and biological processes. Designing and synthesising anion receptors are of high importance in host-guest chemistry due to their significance in developing chemical sensors and membranes for selective transport and separation of anions. In particular, the synthesis of colorimetric anion sensors is of great importance because visual detection can offer qualitative and quantitative information. Efforts have been made to develop hydrogen-bonding donors (receptors) containing imine, amide, urea, thiourea, and also transition metal-based receptors. Urea and thiourea groups are powerful hydrogen bond donors, which have shown selective anion recognition through hydrogen bonding. C3v symmetrical systems seem to create a suitable cavity for anions, so long as those receptors have hydrogen bond donors able to bind the guest of interest.
Many important molecules, both organic and inorganic, contain tetrahedral anions, such as phosphate and perchlorate. An anion receptor having a cavity that is selective for tetrahedral anions and that takes advantage of the strong hydrogen bonding capabilities of thiourea is desirable. Thus, tristhiourea tripodal metal complexes solving the aforementioned problems are desired.